Walker says he is confident the state will successfully appeal the ruling, but regardless of the ultimate fate of the law -- known more commonly as Act 10 -- here are a few quick takeaways of what Friday's development could mean on the campaign trail in a state that is being contested at the presidential and Senate levels:

* Labor's enthusiasm could be rejuvenated: Walker's victory in the June recall election was a big blow to organized labor, which invested significant resources trying to defeat him. Friday's ruling is a much-needed bit of good news for public unions -- even if it is only temporary. Democrats all the way up to President Obama are counting on labor's support this fall. A movement that has been knocked down repeatedly over the past two years might find some new momentum for the stretch run of the campaign.

* Wisconsin's polarization isn't going away: The 2011 anti-Walker protests in Madison were followed by a contentious state Supreme Court election, and then two rounds of recalls that brought millions of dollars of outside money into the state. The result was a sharply polarized electorate in which undecided voters have become very rare and most people have formed hardened opinions on one side or the other.

In his June victory speech, Walker sounded a conciliatory note, urging both Democratic and Republican lawmakers to join him for beer and brats. But the possibility that strident partisanship will give way to compromise may have been reduced by Friday's ruling, because it brings to the surface once again the issue that so heavily divided the state.

* The debate over collective bargaining isn't over: When Walker won his recall, many observers thought that would be the last (major) word in the Wisconsin debate over Walker's controversial law. Republicans won the reaffirmation of their policies they had sought, while Democrats were forced to deal with the defeat at the highest level.

Friday's decision could re-open the debate. Democrats in Wisconsin who for two years have sought to use Walker as a political bogeyman lost some momentum when he won the recall. They may find new strength in their arguments, if Act 10's legal standing isn't sound. At the same time, the Republican base that was so energized to turn out for Walker this summer may return in major way this fall. In the Senate race in particular, former governor Tommy Thompson (R) and Rep. Tammy Baldwin (D) could be debating the issue a lot more than they might have originally thought.

* The "judicial activism" debate could re-emerge: In his statement on Friday, Walker called Dane County Circuit Court Judge Juan Colas a "liberal activist judge," a line that more Republicans could repeat in the days to come, as Walker's allies seek to discredit the judgement.

Obama attracted a lot of attention earlier this year when he warned the "unelected" Supreme Court against striking down his health care reform law, saying such a move would be "an unprecedented, extraordinary step of overturning a law that was passed by a strong majority of a democratically elected Congress."

When charges of activism are thrown around, a larger public debate can ensue, and the Wisconsin ruling could trigger such a debate over the influence of partisanship on the legal system.

Sean Sullivan has covered national politics for The Washington Post since 2012.

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